1. Field of the Invention
The invention relates to a method for manufacturing a piezoelectric film wafer, a piezoelectric film element and a piezoelectric thin film device.
2. Related Art
A piezoelectric material is processed into various piezoelectric elements in accordance with different purposes, particularly, it has been widely used for functional electronic components such as an actuator for generating deformation by applying voltage or sensor for generating voltage from the deformation of elements in a reverse way, etc.
As the piezoelectric material used for an actuator or a sensor, a lead (Pb)-based dielectric material having large piezoelectric characteristics, especially, Pb(Zr1-xTix)O3-based perovskite-type ferroelectric called as “PZT”, has been widely used, and the piezoelectric material is generally formed by sintering oxide which is formed of individual elements.
In recent years, it is desired to develop a piezoelectric material not containing lead from environmental consideration, and thus, potassium sodium niobate (general formula: (K1-xNax)NbO3 (0<x<1)), hereinafter referred to as “KNN”, etc., has been developed. Since KNN has piezoelectric characteristics comparable to PZT, it is expected as a potential candidate for a Pb-free piezoelectric material. Examples of a lead-free piezoelectric film using this kind of piezoelectric material are proposed in the JP-A 2007-19302 and JP-A 2007-184513. In addition, it is commonly assumed that it is effective to form a film by providing the piezoelectric film with a plane orientation to provide the piezoelectric film having good piezoelectric characteristics. For example, it is studied to provide a piezoelectric film with the orientation by forming the piezoelectric film on a base layer having an orientation.
It is possible to manufacture an inkjet printer head or an angular rate sensor with small environmental burden by forming a Pb-free piezoelectric film as a piezoelectric film. Accordingly, when an actuator or a sensor is manufactured with using the Pb-free piezoelectric film, it is required to process the Pb-free piezoelectric film in a beam shape or a tuning-fork shape. In etching of the Pb-free piezoelectric film, Cl-based reactive gas is used as a reactive gas, e.g. in C. M. Kang et al “Etching Characteristics of (Na0.5K0.5)NbO3 Thin Films in an Inductively Coupled Cl2/Ar Plasma”, Ferroelectrics, 357, pp. 179-184 (2007).